Cyclic- and Dwell-Fatigue Crack Growth Behavior in a Phase Transformation Strengthened Disk Superalloy

A follow-on study was performed on NASA’s recently developed nickel-based P/M TSNA-1 diskDisk alloy to evaluate the influence of processingProcessing on the alloy’s mechanical propertiesMechanical properties. The composition of the alloy was tailored to improve the high-temperatureHigh temperature creepCreep strength through transformation strengthening of precipitatePrecipitates phases. Initial alloy developmentAlloy development was done utilizing HIP processingProcessing. The follow-on study evaluated the properties of the forged version of the alloy which provided for a more realistic processingProcessing history similar to that utilized in the engine industry. The creepCreep performance of the forged material significantly exceeded the original HIPHot Isostatic Pressing (HIP) material and outperformed alloys like LSHR and ME3 by an order of magnitude. The TSNA-1 alloy’s cyclic and dwell FCG behavior was also characterized. While the HIP condition of the alloy exhibited very poor dwell FCG resistance in comparison to the LSHR P/M diskDisk alloy, the forgingForging processed TSNA-1 drastically improved the crack growth behavior. In the forged condition, both cyclic and dwell FCG behavior of the alloy were equivalent to a current LSHR P/M alloy.